Rat Bike Rebirth

Discussion in 'Photos & Bicycle Builds' started by floridaboy, Jul 30, 2016.

  1. floridaboy

    floridaboy Member

    Hi, I have a rat bike i built awhile back and have put it back on the road again. The bike is a old Murray that i recycled from a trash pile. The engine is a Dax F80 (66cc.). It has a Manic Machanic clutch activator. It has a 40 tooth sprocket and adapter also Manic Machanic. The engine has some mild porting and will be getting a new RT carb. from Dax. I have had this engine for about 8 years with no problems.
     

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  2. Randall

    Randall Member

    I like your fuel tank configuration.
     
  3. JunkyardDog

    JunkyardDog Active Member

    I love the look, but no front brake, rear coaster brake, rag joint rear sprocket, and that cheap POS tensioner scare the crap out of me. The results can be disasterous when that tensioner gets pulled into the rear wheel. As far as I know, Murray bikes are American made, so it should be strong enough.
     
  4. floridaboy

    floridaboy Member

    The bike now has a front brake i was waiting for it when the picture was taken. That is not a rag joint as i said it is a sprocket adapter from Manic Machanic. The chain adjuster is brazer to the frame. The fuel tank is from a Lawn Boy mower.
     
  5. JunkyardDog

    JunkyardDog Active Member

    Ok, front brake and no rag joint. That's good. I would still replace the tensioner with an engine mounted one. Even if the bracket cannot turn on the frame, it can still bend, or that white plastic roller can break, allowing the loose chain to come off the sprocket and lock up the rear wheel. On a single speed it might be possible to remove some links from the chain and adjust it by sliding the axle in the frame. I know that could throw the pedal chain out of adjustment, but you should be able to get it close with a half link. I would much rather the pedal chain be a little off than the motor chain. My Trek 800 used to be an 18 speed, and I converted it to a single speed, by removing the derailleurs and all but the smallest front sprocket. I put the chain on the largest sprocket on the rear wheel, so I would have a really low gear. I couldn't get the chain adjusted perfectly because of the vertical rear dropouts, so I rode it with the chain a little bit loose for awhile, the finally got a new chain and reinstalled the rear derailleur just to act as a tensioner. No motor chain, it's friction drive.
     
  6. floridaboy

    floridaboy Member

    Ok , here is the newest pictures. Here is the way it is now. The roller is a wheel from roller skates.
     

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    Last edited: Aug 7, 2016
  7. JunkyardDog

    JunkyardDog Active Member

    Good deal. Now I like it. The reason I make such a big deal about that tensioner is because one almost got me killed a few years ago. I was riding in the bike lane, just a couple feet from 45-50 mph traffic, when it got pulled into the rear wheel, locking it up. I went down hard. Fortunately I fell to the right, had I fallen to the left I would have been run over by traffic.
     
  8. floridaboy

    floridaboy Member

    Well i was thinking about what you said about the chain tensioner and thought i should brace it better . Thanks for pointing out what you thought was a weak spot. After i am not a young man any more and can't take those hard hits anymore . Going to be putting my Electra Cruiser back on the road with a new Staton FD with a Zenoah G43 with a 1.125 drive roller. This is my main bike i ride because i peddle it till i get tired and come home under power. The Staton is replacing a home built Ryobi FD drive i built. This bike has had two in frames and two FD in the ten years that i have it. Many good fun miles.
     
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